Why are you worried about power consumption?
For the A10 I would recommend A75 or A85 depending on pricing in your country. ASRock is usually quite competitive.
The HTPC is bound to be on most of the time (maybe not quite 24/7 but close). Higher consumption --> higher cost and potentially higher temperature --> more noise from the fans?
Also, would not the i5 'age' better (especially if I decided to go for a separate graphic card down the road)?